Characterization of the mass transfer fluxes in a capacitive desalination cell by using FeIII(CN)63−/FeII(CN)64− redox couple as an electrochemical probe

Abstract

This paper focuses on the characterization of an electrochemical flow cell designed for capacitive desalination, by using the Fe III (CN) 63− /Fe II (CN) 6 4− redox couple as an electrochemical probe. A relationship between the potential scan rate and the electrolyte flow rate has been first established by defining a dimensionless number, θ. Depending on the θ values, two regime domains -dependent and non-dependent from the flow rate -have been defined. The dimensionless number θ was found to be of great help for defining the suitable flow rate for several carbon based electrodes exhibiting different surface area, using Fe III (CN) 63− /Fe II (CN) 6 4− redox couple as an electrochemical probe. The proposed electrochemical analysis is a way to optimize the performance of an electrochemical flow cell for capacitive desalination applications.

A critical review on the electrosorption of organic compounds in aqueous effluent – Influencing factors and engineering considerations

“…Dimensionless times have also been proposed in the literature, such as G, T and  (Chue et al, 1993;Sene et al, 2019). G refers to the competition between the electrical potential wave and the sorption wave (Chue et al, 1993), whose value is compared to T, which is the reduced time (Chue et al, 1993).…”

“…At T > G, the potential is almost constant in the material, and the concentration of the targeted compound(s) in the effluent begins to decrease. More recently,  has been suggested as dimensionless time to define the flow regime, i.e., either the permanent or non-permanent domains (Sene et al, 2019). It allows for estimating the optimal flow rate that will give an optimal charge transfer (Table 5).…”

Capacitive de-ionisation: An electrochemical perspective

“…An attempt to relate the electrochemical signal to mass-transport within the CDI cell has been reported by Simon and co-workers. They added a simple redox couple (the ferri/ferrocyanide couple) to the solution and used the Faradaic response of the couple as a proxy to understand mass-transport in the CDI case, comparing the simple case of a flat Pt foil, then extending the experiments to activated carbon films where the transport will become dominated by inter-pore transport [16]. Only empirical relations between the current and the flow regime are drawn, which is surprising because channel and tubular configurations exist which allow quantification of current in terms of flow rate, at least for the case of non-porous electrodes [17].…”